Question 73504
{{{x*sqrt(18)-3*sqrt(8x^2)}}}
{{{x*sqrt(2*9)-3*sqrt(2*4*x^2)}}}Rewrite terms inside square root
{{{x*sqrt(2)*sqrt(9)-3*sqrt(2)*sqrt(4)*sqrt(x^2)}}}Rewrite roots using {{{sqrt(xy)=sqrt(x)sqrt(y)}}}
{{{x*sqrt(2)*3-3*sqrt(2)*3*x}}}Notice how we have a common term of {{{sqrt(2)}}} 
{{{3x*sqrt(2)-9x*sqrt(2)}}}combine these terms
{{{(3x-9x)*sqrt(2)}}}Simplify
{{{-6x*sqrt(2)}}}